Duplicating apparatus



Dec. 6, 1927. 1,651,924

E. LICHTENSTEIN DUPLI CATING APPARATUS Filed June 2.. 1925 Figi,

Patented Dec. 6, 1927.

UNITED STATES PATENT v*o1-Fica E'DMUND LICHTENSTEIN, OF BERLIN, GERMANY, ASSIGNOR TO DEUTSCHE MASCHIN- ENBAU'- 'UND 'VERTRIEBS-GESELLSCHAFT M. B. H., OF BERLIN, GERMANY, FIRM.

DUPLICATING APPARATUS.

Application led June 2, 1925, Serial No. 34,453, and in Germany July 21, 1924.

This invention relates to duplicating apparatus and more particularly to devices for tensioning flexible printing metallic foilson the impression cylmder'of rotary printing 5 machines.

Duplicators being at the present time simple marketable articles sold according to catalogue and operable by an operator in a simple manner, it may happen that the 1o sheet of foil which has been provided ywith the written matter in a typewriter and which written matter is therefore visible on both sides of the sheet is stretched on the impression cylinder in a reverse manner that is to say with the surface prepared for printing placed downwardly by an unskilled operator. Edorts have been made to opercome this by erforating the sheets with unequally space holes.

It has been found however, that in rotary printing of the sheet 1s lirmly secured to the impression 'cylinder and the other end ofrthe sheet is resiliently attached to the impression cyl inder the former end of the sheet is in operation worn more rapidly at the points of attachment than the latter end with the result that the sheet is rendered useless prematurely. Y

To obviate this disadvantage the unequally spaced holes are according to the present invention provided at both ends of the sheet and are arranged symmetrically in such a manner that while the sheet is prevented from being clamped in position with itswrong side u it is also capable ofbeing turned througran angle of 180 'about an axis at right angles to its plane for the purpose of interchanging the firmly and resiliently clamped ends before one of them is entirely worn out.

In order that the invention ymay be more easily understood and readily carried into effect reference L-may now be had'to the ac- 15 companying drawings illustrating av preferred embodiment thereof and in which Fig. 1 .is a view of the tensioning roller of a'duplicating machine.

Fig. 2 is a cross section of the impression cylinder of a duplicating machine and Fig. 3 is a view of a sheet according to the invention.

The sheet ais drawn tightlydboutthe surface of the cylinder c as shown in Figure 2 I and has one of its ends attached thereto by machines in which one end` pins b. The other end of the sheet is attached by pins d to the tensioning roller f which is under the action of a spring g and is adapted to cause the sheet to closely embrace the periphery of the cylinder.

The perforations of the sheet are preferably such, that the distance 'between consecutive holes 71, is diierent. As shown in Figure 3 it will be noted that the holes in the top end of the sheet are such that starting from the left the distance between them continually increases. At the bottom end the arrangement is exactly the reverse. With this formof connection it is quite impossible to place the sheet on the pins with the'wrong face uppermost.

As shown in the drawing the unequally spaced perforations at the two ends of the sheet are arranged symmetrically according to the invention, in such a manner that while the sheet is prevented from being placed ou the impression cylinder with the wrong face uppermost it is capable of being turned through 180 about an axis at right angles to its plane so as to reverse the ends of the sheet, and therefore it is possible to ,turn the sheet through 180 in the plane thereof about an axis at right angles to this plane. This is particularly important where the Sheet is clampedrigidly at one end and resiliently at the'ot-her end, but is also of advantage for the many other methods of attachment in use. v

The metal foil being an exceedingly delicate membrane is ordinarily but` feebly resistant to the strains to which it is subjected incidental to its application to the cylinder of the duplicator and to its subsequent usein printing, so that when fastened on the studs in the usual manner by one or two holes, it is soon torn oli'. But, in the present instance, in which a plurality of transversely distributed holes are used cooperating with a like member of studs on the duplicator, the stencils are substantially uniformly distributed over the w'alls of all the holes on one end of the foil sheet so that the sheet is not overstressed at any one point, the life cf the sheet beingkthereby prolonged.

For particular constructions of duplicating machines the perforation intervals could .also be chosen variably so as to 4prevent unsuitable sheets from being used in the machine.

What I claim is:-

l. Duplicating apparatus comprising, an impression cylinder, a tension roller operatively associated therewith, a row of pins on the impression cylinder, a row of pins?" on the tension roller, the distances between successive pins 1n each row mcreaslng 1n the sume ratlo but from opposite ends of the v cylinders.

2. A. sheet for use in duplicating appa- EDMUND LICHTENSTEIN. 

